The objective of this research project is to develop a rapid, simple and inexpensive immunoassay test kit for antibodies to the causative agent of syphilis. Antigens will be coated onto the center of filter paper as a small spot. In the assay, serum sample, enzymelabeled antibodies to human immunoglobulins (conjugate) and finally enzyme substrate are sequentially added dropwise to the antigen spot, without incubation. The results are read visually. The total time of the assay will be less than five minutes, including color development, depending on the volume of sample and reagents to be used. This is a Phase I SBIR contract.